Strap joint forming tool



March 27, 1934. H. c. PORTER STRAP JOINT FORMING TOOL Filed Jan. 25, 1932 E 5. a wa 2 Z L 2 i? Q 7 7, 2 .1 K1 1? m m? I @W k w z. a y I: 4\W 9 ,W & z MM a 7. a z

Patented Mar. 27, 1934 I "Ulll'lED STA TEs.

PATENT OFFICE to Signode Steel Strapping Company, Chicago, 111., a corporation of Delaware Application January 25, 1932, Serial No. 588,556

9 Claims. (Cl. fil 9.1)

This invention relates to strap joint'forming tools, and more particularly to such tools for interconnecting the overlapped ends. of package banding straps by a continuous edgewisesqueea Qing motion;

In Patents No; 1,038,109 to E. E. Flora and No. 084,935 and. No. 1105191 to E. E. Flora and J. F. Murphy are shown tools of this general type. These tools comprise essentially two jaws mov- I able toward and from each other, equipped with deforming pins adapted to engage opposite edges of the'overlapped strap ends and having a centrally disposed chair or anvil-like seat therebetween, such'chair having raised ends or laterally disposed flanges, the function of which isto insure that the edges of thestrap'are in proper position relative to the deforming pins when'initially engaged therebetween. The forcing together of the jaws of these tools causes the de- 'l forming pins to-engage' opposite edges of the overlapped'strap ends, and the encircling sleeve if one is used, and, upon further-movement; forces the edges of the strap and sleeve downwardly and inwardly into a position substantially at right 5 angles to the initial plane of the strap. The formation of the edge crimps or deformations incidentally causes the central portion of the strap ends and sleeve to offset itself outwardly into a hump, which'hump merges gradually or blends into the straight strap portions at a distance beyond the edge deformations dependent upon the stifiness of the strap and/ or the sleeve if a sleeve is used. In the joint the longitudinal separation of the overlapped strap portions, when under tension, is resisted by complementary opposing angular shoulders in the marginal deformations thereof.

These prior tools produce joints in which resistance to'longitudinal separation varies with variations in the stiffness of the strap because they do not force the edge crimps or deformations closely to conform to the curvature of the forming pins and consequently the stiffer the strap the less the obliquity of the complementary angular shoulders. And as resistance to separation decreases as the obliquity of the complementary angularly disposed shoulders decreases, the stifier the strap the weaker relatively are the joints formed by these prior tools. One of the objects of my invention is to'provide a tool which will provide uniformity of interlocking strength between the overlapping strap ends without regard to variations in the stiffness of the strap,--such result being attained by controlling theobliquity of the complementary angular shoulders irrespectiveof the stiffness of the strap material.

The prior tools, because they do not definitely define the outwardly offset hump,'produce a joint in which the hump is not supported throughout its length. The result is that under tension the humped portion flattens relatively easily and tension strain isconcentrated inor restricted to the inturned edges'of the overlapped strap portions, the central or humped portion taking substantially no part of the strain, and the shoulders straighten out and lose their tension resisting properties.

Another object of my invention is to provide a tool which will form a hump which is supported substantially throughout its length and'thereiore produce a :jointwhcreinthe strain of tension in the strap is substantially uniformly distributed throughout the entire cross section of the strap with the result that the tendency of the complementary angular shoulders to straighten and lessen their power to resist longitudinal separation is reduced to a minimum.

The prior tools, failing to correlate any deformation with the edge deformations to assist the latter in resisting the straightening action of the tension, produce joints wherein only the stifiness of the downwardly directed angularly shouldered marginal portions of the strap resist the tendency of those portions to wedgepast each other under the longitudinal tension to which the strap is subjected.

Another object of my invention is to provide a tool wherein the resistance of the edge portions to this wedging action is reinforced by other portions of the joint.

The prior tools produce a joint wherein there is relatively little pressure (and consequently slight frictional resistance to separation) between the contacting surfaces of the strap in the humped central portion. This characteristic is particularly objectionable where it is necessary or advisable to employ strap with lubricated surfaces or surfaces with a low coeiiicient of friction.

A further object of my invention is to provide a tool whereby heavy pressure is insured between the contacting surfaces of the strap ends throughout the entire deformed region, including the humped portion-thereby producing joints of greater strength with strap having a low coefficient of friction or lubricated surfaces.

With the prior tools it is impossible to produce a joint in the overlapped ends of a strap which is under tension substantially to the point of fracthereon by the shortening of the band in the deforming operation.

' Another object of my invention is to provide a tool with which joints may be satisfactorily made in strap which is under tension substan tially to the point of fracture.

Another object is to provide a tool whereby the obliquity of the angular separation resisting shoulders may be increased without increasing the depth of deformation and thereby strong joints may be made without undue effort.

Another object of my invention is to provide a tool by which joints of equal or greater strength in strap of like stiffness may be produced with shorter deformations longitudinally than is possible with the prior tools.

A further object of my invention is to provide a tool wherein manufacturing tolerances do not result in excessive looseness in the assembly and wherein adjustments to compensate for wear may be readily made.

A further object of my invention is to provide a tool having novel means to resist the deforming pressures while maintaining a conveniently usable size;

Other objects, advantages and capabilities of the invention will appear from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawing, in which Figure 1 is a side elevation of a sealing tool embodying my invention;

' Fig. 2 is a sectional view therethrough, on a larger scale, taken on the line 2-2 of Fig. 1;

Fig. 3 is a sectionalview therethrough taken on the line 3--3 of Fig. 2, and

Fig. 4 is a sectional view therethrough,'on a larger scale, taken on the line 44 of Fig. 1.

Referring to the drawing, the tool 10 comprises, in general, a pair of handles ll and 11", which are shaped at their lower ends to form similar jaws 12 and 12, a pair of side plates 13 and a chair 14, which are assembled together by bolts 15. These bolts pass'through suitable openings in the side plates 13 and in the jaws l2 and 12 located between the side plate 13, and through suitable openings in wings 32 of the chair 14, which wings are located in slots 16 provided in the jaws l2 and 12 as illustrated in Fig. 4. Each side plate 13 is provided with a threaded opening 17 into which the threaded end of one of the bolts 15 is screwed, and an unthreaded opening 18 through which the shank of the other bolt 15 passes freely. As will readily be understood from Fig. 4, this construction renders it possible 'to adjust the assembly to desired accuracy by'screwing the bolts 15 into the plates 13 to the desired extent and then looking the-bolts by means of the nuts 19. The tlneaded openings 17 in the side plates 13 are so located that the rotational friction of the jaws when they are being closed, will tend to tighten the bolts rather than loosen them. However, the lock nuts 19 will ordinarily prevent frictional rotation in either direction.

The handles 11 and 11' are crossed above the position of the bolts 15 as shown in Fig. 1 so that the motion of the handles to bring them together causes a similar closing motion of the jaws 12 and 12. The handle 11 is provided with a pin 20, which projects as shown in Fig. 2, into an arouate groove 21 provided in the jaw 12, the pin and groove being so related that the axes of the bolts 15 will always lie on a plane substantially .to limit the opening movement of the handles.

perpendicular to a plane located centrally between the handles. In this way the jaws 12 and 12 will always have an equal and similar motion relative to the edges of the side plates 13 and the chair 14, which maintain a fixed relation to the bolts 15. I

The handles 11 and 11' are provided with stops 22 to limit the closing motion of the handles and jaws. The handles 11 and 11 are provided with faces 23 and 24 which are adapted to interengage It is to be noted that both the opening and closing motions are limited by portions of the handles other than the working parts of the jaws, which sustain the greatest force and are subject to the greatest possibility of damage.

The jaws 12 and 12' are provided with lips 25 which are adapted to approach each other closely in the closed position of the tool, as shown in Fig. 1. The construction of the tool allows it to be opened to the extent that. these lips will be separated sufficiently to pass beyond the edges of the fiat straps and sleeve when the tool is applied thereto in the initial step of forming the joint.

The jaws 12 and 12' are provided with undercut 100 recesses 26 and 26 respectively, and the side plates 13 are provided with recesses 2'? in their lower edges, which recesses cooperate to form an opening of substantially the dimensions of the superposed band ends, and the surrounding sleeve if any is used, when the tool is closed as in Fig. 1.. Substantial clearance is provided within the jaws on the inner side of the lips 25 to provide space for the formation of the joint, this space being restrictedonly by the chair 14, as will be seen in Fig.2, and by the forming pins, as will be seen in Fig. 3.

In each jaw midway between the side plates 13 and within the recesses 26 and 26', is inserted a forming pin 28 provided with a forming nose 29 which is adapted toengage one edge of the strap and force it into deformed shape, substantially at right angles to its initial position and to the seat of the chair 14.

The chair 14 is provided with a central seat 30 and lugs 31 which project downwardly beyond the, central seat. These lugs are located one on each side of the plane of motion of the forming pins. The chair is preferably made as shown in Fig. 4, with offset wings 32 which are inserted in the slots 16 of the jaws 12 and 12, the wings 32 being so located that a support of. solid metal is provided for each of the lugs 31. This construction enables this solid metal support to be attained with relatively narrow slots 16, thus providing greater strength of jaw without increasing the width thereof excessively.

It will readily be understood that when the tool is opened to the full extent it can be placed over the strap ends and sleeve at the position at which the joint is to be made, with the lips 25 located to the outside of the edges of the strap and below the same. This positioning of the tool locates the strap within the recesses 27 of the side plates 13. which serve to hold the overlapped strap portions (and the sleeve if one is used) in the correct position to be properly engaged by the forming pins. If a sleeve of the open flange type is used, the initial movement in the closing of the jaws will cause the lips 25 to bend the downwardly hanging sleeve-flanges around and below the strap into surrounding engagement therewith. The lips 25 approach each other beneath the strap and serve to prevent the escape of the strap and leeve metal out of the tool. The lateral 150 openings defined between the lips 25 and the recesses 27 of plates 13 provide a snug fit for the superposed strap portions and sleeve, hold the end portions of the joint fiat and undeformed during the joint formation.

As the tool is gradually closed the noses 29.

of the forming pins 28 engage the strap edges and bend them inwardly towards each other, forming vertically disposed flanges 33 and a centrally humped portion 34. The lugs 31 of the chair define the extremities of the flanges and the central hump so that they are substantially coextensive longitudinally of the strap. The seat and lugs of the chair cause the flanges to conform closely to the curvature of the noses of the forming pins and tightly squeeze together into tight ribs the various layers of strap in the fold between the hump and the marginal flanges 33 which ribs are coextensive longitudinally with the flanges and the hump. The hump is pressed strongly against the entire inner surface 30 of the chair so that the lugs 31 thereof produce well defined and effective stiffening shoulders where the hump merges into the straight strap portions at opposite ends of the joint.

Thus the tool deforms the overlapped strap ends, and the encircling sleeve if one is used, into complementary separation-resisting distortions the length and other characteristics of which are definitely secured. The joint produced by my improved tool is set forth in detail in my copending application Serial No. 591,063, filed February 5, 1932.

The lugs 31 preferably are not approached by the lips 25 as closely as are the side plates 13 so that they do not exert an excessive clamping action upon the strap, a slight clearance being provided. It has been found in practice that this construction permits the lugs to act as described to define the formation of the hump and of the marginal flanges without applying excessive forces to the straps which might result in the impairment of the strength thereof, particularly at the edges where the marginal deformation starts.

Although the invention has been disclosed in connection with the specific details of a preferred embodiment thereof, it must be understood that such details are not intended to be limitative of the invention, except in so far as set forth in the accompanying claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A sealing tool for producing joints between overlapped portions of metal strap, comprising a pair of jaws movable toward and from each other with the strap portions therebetween, deformers on the jaws which act edgewise upon the overlapped strap portions when the jaws move together to form in such portions complementary separation-resisting distortions, stationary means for holding the overlapped strap portions in proper relation to the deformers, and means cooperating with the jaws, holding means and deformers for defining the length of the distortions produced thereby.

2. A sealing tool for producing crimp joints between overlapped portions of metal strap, comprising a pair of jaws having projecting lips and adapted to receive the overlapped strap portions between them and move toward each other, a

forming pin carried by each jaw, said pins engaging opposite edges of the strap and deforming the same as the jaws move together, a stationary chair having protruding lugs at opposite ends and against which the forming pins tightly press the sides of the strap, the lugs serving to limit the longitudinal extent of the deformations produced by the forming pins, and means located beyond each end of the chair to locate the overlapped strap portions in proper relations to the jaws and forming pins.

3. A sealing tool for producing joints between overlapped portions of metal strap, comprising a pair of jaws adapted to receive the overlapped strap portions between them and move toward each other, a stationary chair lying between the jaws and having spaced projecting lugs each disposed transversely of the longitudinal direction of the strap, a forming pin carried by each jaw, said pins engaging opposite edges of the strap and deforming the strap outwardly against the chair lugs whereby the lugs serve to limit the longitudinal extent of the outward deformation, and means located outside of each jaw to locate the overlapped strap portions in proper relation to the forming pins and chair.

4. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a pair of plates one on each side of the jaws, each plate having a threaded and an unthreaded opening therethrough, and a bolt securing each jaw to said plates, each bolt passing freely through an unthreaded opening in one plate and being threaded into a threaded opening in the other plate.

5. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a pair of plates one on each side of the jaws, and a bolt securing each jaw to said plates, said bolts being oppositely directed, each passing freely through an opening in one plate and being threaded into an opening in the other plate, said bolts being arranged so that the closing movement of the jaws tends to tighten the bolts.

6. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a chair having wings adapted to enter slots in said jaws, and bolts passing through said wings and jaws, the wings on opposite sides of the chair being located adjacent opposite ends thereof.

7. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a chair having a wing adjacent each end directed outwardly in opposite directions, said jaws having slots adapted to receive said wings, and bolts extending through said jaws and wings.

8. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a chair having a lug at each end and a wing beneath said lug, said wings being directed outwardly in 0pposite directions, said jaws having slots adapted to receive said wings, and bolts extending through said jaws and wings.

9. A strap joint forming tool comprising a pair of jaws adapted to approach each other, a chair having a lug at each end and a wing beneath said lug, said wings being directed outwardly in opposite directions, said jaws having slots adapted to receive said wings, a pair of plates one on each side of the jaws, and bolts extending through said jaws, wings and plates.

HOWARD C. PORTER. 

